Description: (Taken directly from the application) The techniques of modern mouse genetics have provided extremely important tools in biomedical research. The generation of transgenic mice has allowed investigators to examine the roles of genes involved in a wide variety of disease processes. The ability to generate specific mutations in genes of interest, including both knockouts and knock-ins, has expanded the power of this approach, allowing the identification of gene regulating immune responses and autoimmunity, as well as genes involved in susceptibility to disease. In addition, these techniques have provided a straightforward means to generate mouse models of important human diseases. The Transgenic/Knockout Mouse Core facility at UMMS currently generates transgenic mice for the analysis of gene function and regulation in intact animals. Transgenic animals are generated by pronuclear injection of DNA constructs into fertilized one-cell mouse embryos, followed by oviduct transfer of the injected embryos into foster mothers. The facility is currently expanding to provide gene targeting (knockout and knock-in) services. As of July 1998, the facility began providing the services of embryonic stem cell injections into 2.5 day mouse blastocysts, followed by uterine transfer of injected embryos into foster mothers. In the near future (by July 1999), the facility will begin providing embryonic stem cell culture services, assisting investigators in growing, transfecting, selecting, and cloning embryonic stem cells for gene targeting purposes.